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Holy Orders is the sacrament through which the mission entrusted by Christ to
his apostles continues to be exercised in the Church until the end of time:
thus it is the sacrament of apostolic ministry. It includes three degrees: episcopate,
presbyterate, and diaconate.

(On the institution and mission of the apostolic ministry by Christ, see
above, no. 874 ff. Here only the sacramental means by which this ministry is
handed on will be treated.)